1. Technical Field
The present disclosure relates to driving LED (Light-Emitting Diode) lamps and, more specifically, to adaptively dimming the LED lamps.
2. Description of the Related Arts
A wide variety of electronics applications now use LED lamps. These applications include architectural lighting, automotive head and tail lights, backlights for liquid crystal display devices, flashlights, and electronic signs. Compared to conventional lighting sources, like incandescent lamps and fluorescent lamps, LED lamps have significant advantages. These advantages include high efficiency, good directionality, color stability, high reliability, long life time, small size, and environmental safety. In fact, these advantages have helped drive the adoption of LED lamps in applications that traditionally use incandescent lamps.
In some applications, however, LED lamps have not been adopted as being suitable replacements compared to other lighting methods. For example, in applications where the brightness of the light source is adjusted, such as in a dimmable lighting system, methods employed to drive an incandescent lamp, if applied to an LED lamp, may cause the LED lamp to prematurely turn off when the LED lamp is in an ON phase, resulting in a perceivable flicker. Techniques employed to reduce flicker include adding multiple sink current paths to a TRIAC dimmer to provide additional current to the dimmer to reduce flicker and meet the TRIAC dimmer turn-on current demands. But these techniques increase power loss and lack the ability to adapt to changes in system operating conditions.